The subconscious mind is a very powerful thing. Our brain is constantly taking in a vast amount of information at all times and must decide which information to focus on. This is what we perceive to be reality. So when a person has a NDE and they are called NEAR DEATH for a reason, as in NOT dead..... the subconscious mind plays a lot of tricks on you.
About the seeing your body from a far. I've had this happen to me in dreams. It's not an uncommon thing to have a sort of "projection" where you are viewing yourself from another spot in the room. Completely normal experience and happens all the time. I've had this happen to me on at least two separate occasions during sleep where I thought I was awake but felt like I was disembodied and viewing myself from above or from across the room. In fact I was asleep in some sense, my physical eyes were seemingly open and I was looking around the room from my vantage point laying on my stomach then all of a sudden I was across the room about 4 feet off the ground viewing my body lying on the bed with a silver string or cord going from where I perceived myself to be over to my body on the bed.
This was merely a dream for I woke up and was back in my own real conscious body and for a moment I was paralyzed. This is known as sleep paralysis and is very very common. Chemicals in the brain are released during deep dreaming to prevent your body from acting out your dreams, this is scientific fact, not demon possession or something crazy like that.
My point here is that as another poster said, ALL near death experiences can be explained. None of them are the same thus pointing to "Unreality" and not one singular "Reality". It's nonsense.